Wide open: That's the phrase John Medeski uses to describe his bandmates' musical sensibilities, the attitude he seeks in himself, and the spirit of musical adventure that Medeski Martin & Wood have pursued for two decades. The trio's amalgam of jazz, funk, "avant-noise" and a million other musical currents and impulses is nearly impossible to classify, which is just how they like it. Medeski's keyboard excursions, Chris Wood's hard-charging bass lines and Billy Martin's supple, danceable beats have come to resemble a single organism, moving gracefully between genre-defying compositions and expansive improvisation atop a relentless groove.

Floridian Medeski had his first out-of-body experience playing a Mozart piano sonata as an adolescent. He soon began playing at every opportunity – from school musicals and talent shows to marching band, in which he served as a percussionist—and had his mind blown by an Oscar Peterson record. As a teen, he formed his own jazz-fusion trio and was invited to tour Japan by legendary bassist Jaco Pastorius. He made his way to the New England Conservatory of Music (NEC) and entered its boundary-pushing Third Stream department, which nurtured his improvisational impulses and encouraged him to find his own musical voice. He worked as a sideman in Boston and rediscovered roots music playing seven nights a week Mr. Jelly Belly.

California-born, Colorado-bred Wood, meanwhile, learned folk and blues songs at the feet of his musician/biologist dad and poet mom, swooned at the fearless innovations of Mingus and Monk, attended NEC and eventually studied with Geri Allen, Dave Holland and other luminaries. His apprenticeship with these powerful music figures was, he admits, a humbling one. "Sometimes my lesson would consist of me improvising for an hour with Geri watching, " he relates. "It was terrifying, because it exposed every weakness. But the more you accept who you are, the more free you are to express that. Your bag of tricks as a player becomes a doorway to infinite possibilities. "

Martin, who'd grown up in New York and New Jersey, imbibed a range of musical currents from his classical violinist father and Radio City Rockette mother, but it was his older brothers who first exposed him to rock and soul. He fell in love with Hendrix, James Brown, Sly Stone, Zappa and KISS and began bashing his uncle's kit; soon he was in the jazz band at school, then at the preparatory division of the Manhattan School of Music. As a musical omnivore in New York City, he studied with assorted greats, mastered an array of percussion instruments, formed the samba band Batucada and played with everyone from jazz-pop superstar Chuck Mangione to Bill Frisell to New York's avant-garde heroes the Lounge Lizards.

Though they started out with a more-or-less straightforward piano-bass-drums jazz setup, the threesome expanded their sound with unusual configurations. Medeski added electric piano (outfitted with distortion pedals and other effects), and began switching back and forth among Hammond organ, Clavinet, Mellotron and other keys. Wood alternated between stand-up and bass guitar, stuck paper behind his strings for a "snare" effect and occasionally employed a drumstick as a slide. Martin, who enjoys, in his words, "the whole pots and pans approach, " began keeping an international assortment of percussion instruments in his battery, as well as objects for banging that are not typically considered musical. "You need to be in touch with that feeling you had as a child when you listened to sound, " Medeski insists. "Everything going on around you is music. When you're in touch with that, you can play from that deep place more easily – you can create music with real freedom and openness. "

MMW has also backed up a diverse roster of artists, including punk godfather Iggy Pop (both live and on his album Avenue B), R&B sax giant Maceo Parker, MacArthur Genius Grant recipient John Zorn and pop singer-songwriter Natalie Merchant.

The band members have also kept things fresh by pursuing scores of other projects. Medeski produced two albums by the Wood Brothers, Chris Wood's rootsy partnership with his brother, Oliver, as well as work by the Dirty Dozen Brass Band; has played with a dazzling array of artists, including The Word with Robert Randolph, Ray LaMontagne, The Blind Boys of Alabama, John Zorn, Trey Anastasio, Susana Baca and the rock band Grizzly Adamz; fronted his own band, John Medeski & The Itch; and performed as a solo pianist. He and Martin have also performed and recorded as the duo Mago. Martin, for his part, has recorded several solo discs and an album of breakbeats (under his own name and as Illy B), collaborated with DJ Logic, DJ Spooky, Dave Burrell and other artists, authored a book, pursued his own visual art, and produced and directed Fly in a Bottle, a feature-length documentary film about the making of the Radiolarian series. The Wood Brothers have released three LPs and an EP of cover songs and toured with the likes of Zac Brown Band, Levon Helm, Bruce Hornsby & The Noisemakers and k. d, Lang.

The three also conduct a yearly musical retreat, Camp MMW, in the Catskills; with music classes, seminars, films, guest teachers and jam sessions, the August gathering encourages promising musicians of all stripes to get out of their comfort zones.

Their reflections on having reached the extraordinary milestone of playing together for some 20 years? "We're old motherfuckers, man, " Medeski replies with a laugh, adding, "We're in a really good place. We've been writing a lot of new music. We always want to create a certain vibration in the evening – if we're doing something new and feeling the excitement, that'll do it. "

"Musically, we're changing all the time," Martin asserts, adding that the band's constant improvisation produces moments when "We look at each other like, 'Oh my God, how in the hell did we just decide to do that?' We look at each other with our mouths open sometimes, and that's the beautiful thing about it."

"This band is each of us expressing who we really are," summarizes Medeski. "That's all."